apache/hadoop · error · RuntimeException

Not invertible

Error message

Not invertible

What it means

Error "Not invertible" thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/rawcoder/util/GF256.java:228

    }

    for (int i = 0; i < n; i++) {
      outMatrix[i * n + i] = 1;
    }

    // Inverse
    for (int j, i = 0; i < n; i++) {
      // Check for 0 in pivot element
      if (inMatrix[i * n + i] == 0) {
        // Find a row with non-zero in current column and swap
        for (j = i + 1; j < n; j++) {
          if (inMatrix[j * n + i] != 0) {
            break;
          }
        }
        if (j == n) {
          // Couldn't find means it's singular
          throw new RuntimeException("Not invertible");
        }

        for (int k = 0; k < n; k++) {
          // Swap rows i,j
          temp = inMatrix[i * n + k];
          inMatrix[i * n + k] = inMatrix[j * n + k];
          inMatrix[j * n + k] = temp;

          temp = outMatrix[i * n + k];
          outMatrix[i * n + k] = outMatrix[j * n + k];
          outMatrix[j * n + k] = temp;
        }
      }

      temp = gfInv(inMatrix[i * n + i]); // 1/pivot
      for (j = 0; j < n; j++) {
        // Scale row i by 1/pivot
        inMatrix[i * n + j] = gfMul(inMatrix[i * n + j], temp);

View on GitHub (pinned to 2add963021)

Solutions

1. The generated coding matrix has no inverse; use the standard Vandermonde/Cauchy matrix generation provided by the coder instead of a custom matrix.
2. Verify numDataUnits and numParityUnits are valid for the RS coder.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/rawcoder/util/GF256.java:228 when the library encounters an invalid state.

Common situations: Occurs when GF256 matrix inversion fails because the matrix is singular, typically from invalid erased index combinations. Validate erasedIndexes so the decode matrix is invertible.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/5f92fb1ea33b0720. Report an issue: GitHub.